


Chasing Tail

by LuciferxDamien



Category: Gravity Falls
Genre: Come Inflation, Dry Orgasm, Incest, Knotting, M/M, Post-Canon, Rough Sex, Sibling Incest, Twincest, Werewolf!Stan, Werewolves, werewolf/human sex
Language: English
Status: Completed
Published: 2019-04-20
Updated: 2019-04-20
Packaged: 2020-01-22 22:10:42
Rating: Explicit
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 4,475
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18536461
Author URL: https://archiveofourown.org/users/LuciferxDamien/pseuds/LuciferxDamien
Summary: Ford just needed a few more days to finish his research, and then he could spend time with Stanley. Why was that always so much to ask! Well, maybe Ford should have been paying a little more attention to the phase of the moon…





	Chasing Tail

**Author's Note:**

  * For [draculard](https://archiveofourown.org/users/draculard/gifts).



> This story is set after the cartoon ended. 
> 
> Please make sure to read the tags! This fic contains sibling incest, cock knotting, and werewolf/human sex!

"I know y'had plans t'go out into the woods t'night but..." Stan said, looking a bit sheepish as Ford walked into the kitchen. 

The smell of food had beckoned to Ford, and dinner sounded nice before he and Stanley went out into the woods for some more research! Ford was getting so close to completing this paper, his body abuzz with the thought of submitting it, getting published and… 

And what on earth was that. 

Stanley grinned at him from the far side of the table, about to sprinkle something—chopped parsley perhaps—with a flourish over the... "Is that rotting meat?" 

Stanley's grin vanished, replaced with that frown Ford had come to dread, as it always pretensed a fit of some sort. "It's dinner. Thought we might stay in t'night." 

"You... shouldn't have," Ford said, barely keeping his huff to himself. 

"It was nothin’." Stan shrugged, a grin returning. 

"No, really. You shouldn't have. I'm fairly certain that meat is raw." How did Dipper and Mabel manage to survive an entire summer with Stanley? Those poor children. 

Stan sighed. He bit his lip and Ford felt a tinge of arousal, and mildly regretting that he had been so busy while home in Gravity Falls for this short while. 

The floorboards creaked as Stanley stomped out of the kitchen and Ford only followed once he heard the front door opening. Stanley was was already out in the yard, leaving the door open and Ford just frowned. 

"Stanley, what are you... You can't just leave that mess in the kitchen! And you can't just go out into the woods without some sort of provisions." 

“Y’know, Ford… Y’d think bein’ in that portal woulda made ya less of an asshole, but no. You’re _still_ the same arrogant, unappreciative jackass y’were when…” Stanley stopped all of a sudden, and it was a good thing he did, too. 

Ford had his fingers curled into a tight fist, ready to leap and punch his idiot of a twin right in the jaw if he decided to utter another word. He was seething, grinding his teeth as he stared Stanley down. 

“Forget it, Ford. Jus’ forget it,” Stanley said with a sigh, waving Ford off with a shaking hand. “Jus’ thought that… Never mind.” 

Ford rolled his eyes, arms across his chest. Stanley _always_ did this! It was like nothing had changed, Stanley was still the same impulsive greedy man he had always been, but at least Ford could bite his tongue and keep his lip buttoned, _unlike_ Stanley. 

“I’ll just… head out, then, I guess. Before the moon…” he trailed off, gesturing to the sky as the sun was setting, everything cast in warm, golden and orange hues. 

_Oh…_

**Oh.**

_Oh no!_

“Stan-Stanley, wait!” Ford called after him, but it was too late and his brother had disappeared off into the woods. 

His heart started beating quicker as he looked around, trying to decide what he should do. Why did he always have to be such an idiot?! Ford groaned at himself, so angry that he had forgotten _that_ of all things. 

No wonder Stanley was so upset. His request to stay in made so much more sense, now… 

The full moon would be rising soon and then… Ford bit his bottom lip, still frantic and unsure of what to do. Being an inter-dimensional criminal was so much easier than this, than dealing with his brother and his moods, but now, even that was made harder, after the incident… 

A few months ago, deep in the Romanian woods. They were hunting vampires and… 

They found werewolves, instead. 

Ford had been too curious, gotten too close and then… 

Stanley pushed him out of the way and took the bite, instead, protecting Ford. 

Werewolves were supposed to be part human, and Ford was certain that he could communicate with them, on some level and reason with them, his brother staunchly disagreed, said that they were animals. Stanley had been right _that time_ Ford supposed. 

Damnit. What was he supposed to do now?! He stood no chance of finding Stan out there, if he decided he didn’t want to be found and… And well. Could Ford really blame Stanley for not wanting to come out? 

He supposed not… 

But Stanley _should_ have been more understanding. Ford had been under a lot of pressure to complete his research and… Well. He hadn’t been sleeping much. Again. And just… Couldn’t Stanley _just_ understand?! 

It didn’t matter, there was no reasoning with Stanley at the best of times and right now, when he was on the verge of a transformation, there was even less of a chance of him getting through that thick skull. 

All Ford wanted to do was finish his research paper and then they could… They could do whatever Stanley wanted… 

Why couldn’t Stanley just be reasonable enough to understand that?! It would only be a few more days! 

Well, if Stanley was going to be like that, then fine! Ford huffed, rubbing his forehead as he went back into the Shack. He had research to do. There was so much he still had to learn about Gravity Falls, and he had thirty years to make up for! And a full moon was _always_ a great chance to learn things. Different creatures were out, the forest was abuzz and… 

A howl broke out, birds scattering from the trees in a great flock. 

The sun had yet to die out, however and Ford went back out into the yard, looking over the house and… 

Ah. The moon was already up, large and ominous. 

Ford swallowed hard, looking back into the Shack. 

Soos and Melody were out for the time being, so he and Stanley had the place to themselves, which had been fine, for the most part. The occasional spat, Stanley always being so _needy_ , and Ford just _really_ wanted to get this research paper done and then he could spend whatever time with Stanley, but this paper! 

Another howl and Ford looked out into the forest, the last of the dying light casting everything in an eerie glow. Ford didn’t like it. Something had to be causing this unease. Something he needed to research! 

He went back into the house and gathered his things before setting off into the forest. 

~ ~ ~ 

The first hour had been rather boring, nothing he hadn’t seen before, but then he found tracks. Wolf tracks, but much too large to have been from the animal itself. 

Maybe… Maybe Stanley was making it easy to be found, luring him out, maybe Stanley wanted to help him with his research? There was still so much he wanted to learn about the lycanthropes, and well. Stanley was a pristine subject to study. Well. Maybe not _pristine_ , but he was certainly a lot more amenable than a wild werewolf that wanted to eat him. 

He had been trying to observe Stanley’s behaviour, just before a full moon, but this month, he had just been too busy and well… 

It was really no wonder that Stan found that ‘meal’ appealing, in his current state. There was so much he could learn about the lycanthropes, through his brother, their habits in their human forms, what subtle changes they went through just before the full moon, but… 

Damn this research paper! 

He had so much to do, and just so very little time! 

But this paper, it had to be absolutely perfect. The magnetic field abnormalities of Gravity Falls was the crux of getting his more… otherworldly research out there. If he could just get people to understand and _accept_ things as he knew them to be… 

Ford sighed to himself softly, what a wonderful place this world would become, then. 

He chuckled, setting up and pulling out a few instruments to take some readings; being able to reliably note the differences in the magnetic fields between a night of the full moon and any other night could be key to winning people over to his thinking! 

Very, very important work he was doing… 

Too bad Stanley wasn’t quite able to help him out… Ah well. Ford had managed living in the multiverse for 30 years, he could certainly handle the comparatively mundane woods of Gravity Falls on his own. 

There was, however, an unease in the forest this night. That could have just been Stanley, though, with his bad attitude, skulking around.

It was certainly nothing to worry about. Ford knew he could handle himself.

A shudder ran up his spine as he heard another howl. It was close.

Maybe Stanley had gotten tired of trying to play games with Ford? Good. Then he could help. Or keep him company, or just chase his tail, Ford really didn't care, so long as Stanley wasn’t too much of a distraction and didn't break anything, of course.

Something came rushing out of the woods and it was… 

Ford’s heart was racing as he looked up at Stanley, in full wolf form. Ford was not amused. 

“Damnit, Stanley! I said I was sorry! I’m trying to fix this!” But Stanley wasn’t listening, and Ford had thought he got around that. He knew that Stanley had more trouble understanding, well, more trouble than _usual_ understanding what was going on while he was transformed but… But they hadn’t had trouble in months with communication during the full moon. 

Was Stanley really that angry now? Had Ford really done that much to hurt him? He didn’t mean anything by it, so why did Stanley _always_ have to be so damn difficult, why couldn’t he just understand?! 

Ford supposed it really didn’t matter at the moment; he just needed to get to his tranq gun and… 

And not think about how ineffective that had been the last time… 

Maybe he really should try talking Stanley down, instead and… and maybe he should apologize… 

At the very least, talking to Stanley might distract him long enough for Ford to get to the tranq gun, right? 

Right… 

“Stanley, look…” Ford started with a sigh and that only earned him another snarl, thick, ropey saliva dripping from Stanley’s maw. Why did he think it was a good idea, again, to go out into the forest on the night of a full moon? 

Research, right… 

_"Can't... can't do your research, Sixer, if you're dead..."_

That's what Stanley had said to him, after he took the bite from the werewolf in Romania.

Ford had to admit that Stanley had his own sort of wisdom. 

And he might have hated, just a touch, how much he had missed this kind of danger, staring a creature down, no weapons, just his wit and… 

Another howl sounded from a ways off, distracting Stanley and… And since when did Stanley have that huge scar across his chest? 

Ah. Of course. This werewolf was not Stanley. 

Ford’s heart picked up another beat and he really had to start scrambling for a plan. Talking to _this_ werewolf would do him no good and without Stanley here he was… 

Crashing came from the trees, as if this night couldn’t get any worse. Ford wanted to groan, but he kept himself still; it was useless to make a plan without seeing what fresh hell was coming at him. 

He braced himself, another howl sent chills up his spine. This… This wasn’t going to be good, if he got caught between two werewolves. Well, best case scenario, they would kill or wound one another enough that Ford could get back to the Shack but, when did things ever go as well as they could… 

Another werewolf broke through the brush, growling, snarling as it entered the clearing. It immediately turned toward Ford, up on its hind legs as it threw its head back to howl. 

Was… was that Stanley? 

Ford felt relief wash over himself. That _had_ to be Stanley, the bulk, that familiar, well _somewhat_ familiar growl. Plus the tinge of silver fur that the first werewolf lacked, it had to be Stanley! 

And if it wasn’t, then Ford was going to be in some serious trouble… 

The first werewolf reared up on its hind legs, going right for Stanley, but it didn’t seem to be a match for his brother. Stanley brought one of his powerful paws down, knocking the werewolf in muzzle, as if he were going for it’s eyes. They faced off, growling and snarling, circling as they sized one another up. 

Oh, how perfect, a chance for Ford to get some first hand observations of werewolf self defense! 

Or, so Ford thought, but Stanley made rather quirk work of the other werewolf, clawing, biting, just using brute strength to overpower it until it ran off into the woods. Then, Stanley turned his attention to Ford. Still up on his hind legs, walking over with an awkward gait, chest heaving and… 

"O-oh..." Ford gasped out, seeing between Stanley's back legs was... Stan always did get a rush out of beating up monsters and… 

Ford swallowed hard. They hadn't quite gotten to this yet, but Ford was _very_ interested and… 

Oh... Is that... Is that why Stanley had wanted to _stay in_? 

Ford could be such an idiot sometimes. 

But why couldn't Stanley just speak _plainly_ to him?! Then these sorts of misunderstandings wouldn't arise and… 

Ford found himself pinned to a tree, a snarling Stanley in his face, claws ripping through his coat and Ford swallowed hard. His pants were already feeling tight and he moaned. _This_ , Ford had been _so ready_ for this. Too eager for Stanley, perhaps, as he had insisted upon researching werewolf sexuality and function right away and… 

Stanley had been quite weirded out and upset by that, during his first full moon. He had spent the night in a cage, instead, and Ford was forced to only do menial observations. 

In retrospect, that might have been the wisest decision, working out the quirks and kinks in communication. Maybe, just maybe Stanley wasn't always so clueless and rash. 

Ford reached out a shaking hand, finding blood on his brother’s maw as he tried to pet him. "I'm... I'm all right, Stanley. You... You saved me, and I'm fine." 

Stanley huffed and growled, but he backed off and got down on all fours, nuzzling his way from Ford's chest to his groin. Ford was hard, he knew that and Stanley was sniffing, pushing at him. 

He shuddered and could barely contain himself. If... If Stanley was really ready for that, then… 

Ford popped the button on his fly and Stanley took in a deep breath, backing up a little more and Ford's zipper was down next, shrugging his coat off. It was a warm night, only cool when the breeze blew. He kept his sweater on, and Stanley seemed fine that, but he was growling at him and Ford had to struggle to understand what it was that Stanley wanted. 

He moved forward, reaching out a hand, his cock hard between his thighs, sac drawn up as a breeze gentled over him. How exciting, being in the forest, with Stanley and… 

Ford moaned, feeling Stanley's hot breath on his cock and his brother always did love sucking him but... But Ford did not think he was quite _that_ adventurous at the moment. 

Stan nuzzled at him, sniffing him all over and Ford started to chuckle, brushing him away. "Patience, Stanley, patience. I'll let you... Just..." Ford looked for his pack, kneeling down next to it mostly nude as he dug around for... Ah yes. He always kept lube on hand these days, just incase. 

It was good for more than just sex, after all. 

But mostly, Ford was hopeful to have a romp. 

He settled his coat into the roots of the tree he had been pinned to, setting his pack down, just incase, before he laid down as Stanley drooled, just watching him with intent eyes and Ford found himself blushing. What more could Stanley hear and smell and sense, while in his wolf form? He made a note to ask about that, later. For now, he was just content to lay down and spread his legs for Stanley. 

Stanley sat down on his haunches, his cock hard and dripping beneath him, just watching as he drooled a little more. Ford smirked, taking his glasses off, tucking them into the pack, being a bit of a tease as he took his time settling in. 

Stanley started panting and Ford was amused, stretching out, rucking his sweater up so that his nipples were exposed; Stanley always seemed to like that. He teased one nipple, watching his brother closely for a moment before he let his head fall back, moving down from his chest to his cock, giving himself a tug, to ease off the ache of being so hard and then Stanley whined, like he often did in human form when he was being impatient. 

"All right, all right... Always so impatient..." Ford chuckled and Stanley gave a slight growl. He did so love to tease his brother. 

But the night would not last forever and Ford picked up the lube, coating his finger generously before shifting, getting his hand between his legs. The lube was cold and he hissed at that, like always. Living as an interdimensional criminal for 30 years had done little to temper his dislike of cold lube. 

The first finger had burned and Ford knew that he had to relax. It was difficult, being out in the open, surrounded by gods knew what, and he felt safe with Stanley there, but oh, he was anxious to feel that body on him, familiar and yet totally unknown. The second finger went in smoother and he spread his legs a little more, Stanley panting and licking his lips. 

"Just a little more, Stanley... I'm _hungry_ , too..." he chuckled and teased, a third finger slipping in, Stanley whining at him. Ford was actually quite impressed that Stanley had shown so much patience with him, waiting for him to prep himself; his cognition as a werewolf was impressive. 

He needed to study this some more, really test just how aware a werewolf was… 

A low growl had Ford opening his eyes. Big, bright gold eyes were watching him, Stanley looking impatient as he stood up up on all fours, his cock hard and wet and bobbing. Ford thrust his fingers faster, spreading them and finding he was a touch tight, but their time was still limited and Ford was almost desperate. 

His brother came to him, whining and whimpering, drooling on Ford’s chest and nuzzling at his hip. Ah yes, it would no doubt be difficult to do it in this position. Even if Stanley had mostly humanoid ‘arms’, he was more comfortable on all fours and Ford rolled onto his belly, raising his hips. 

There was a pause, trepidation hanging in the air as Stanley maneuvered. Ford was holding his breath, head down, canting his hips to entice his brother. A warm tongue lapped at his hole and Ford groaned, Stanley seeming to mimic his noises. Claws dug into Ford’s coat and the mossy roots of the tree as Stanley got close to him. 

Weight pressed down into his back as Stanley got on top of him and Ford flipped the lube open, coating his hand, just incase. He breathed out heavy, Stanley shifting on top of him, digging his claws in and Ford was thankful he had chosen to keep his sweater on, to protect himself some. Stanley’s hard cock bumped into his thigh, rubbing against him, but he made no move to push in. Ah, of course. 

“I’m ready, Stanley,” Ford whispered, but Stanley didn’t move, whining at him instead. It seemed it was Stanley’s turn to start teasing him, rubbing his cock against Ford’s thigh. “C’mon Stanley, fuck me…” Ford wasn’t above begging at this point, his cock hard and leaking. Hot breath ghosted Ford’s neck and ear, Stanley leaning down over him, nuzzling into his ear, as if he were waiting for something more. His throat was dry as he tried to swallow, gasping as he felt his brother’s cock pressing into him again. “F-fuck me, like I’m your _bitch_.” 

Stanley growled and wasted no time, his cock hard as he searched for Ford's hole and Ford had to reach down between them and help guide him in, coating his brother’s cock with lube and then _oh_ … Ford was curling his toes. It was rough and sudden, all of the air forced out of him as Stanley pushed in entirely. 

Ford took his cock in hand, holding himself at the base; the absolute last thing he wanted was to blow immediately, like some teenager again. He moaned and Stanley whined, pulling back and driving back in, over and over and over and… 

Ford felt himself getting hot, shifting his weight to his shoulder so that he could tweak a nipple as he let himself be fucked. It was rough and it was fast and Ford didn’t care, his brother’s hot breath on his face, panting as drool dripped from his maw. He groaned, forcing himself to relax, his arousal building low in his gut. 

A breeze blew and Ford tensed as the cold air hit him, and _oh_ that had Stanley’s cock feeling even better inside of him. He was crying out even louder, the thick cock in him hitting all the right places. He knew he ought to have controlled himself more, there was no end to the creatures that they might attract, but to hell with all of that! 

Ford jerked himself faster, his orgasm building quickly. Something even thicker than the cock pumping in and out of him bumped against Ford’s rim, threatening to pop in, stretching him and Ford reached his hand back, feeling around. A warning growl sounded in his ear, but Ford ignored his brother, continuing to probe until he gasped out. 

Oh, wolves had knots didn't they? How fascinating that a werewolf would, as well. He was learning so much tonight, and that excited Ford all the more! 

It felt like Stanley’s cock was starting to swell and Ford’s breath hitched, the thrusts becoming shallower, rubbing over his prostate. The bundle of arousal in his gut was growing and growing, Ford’s sac drawing up tight, tight, tight. He groaned, holding his cock at the base, to help calm himself as he felt his hole being stretched wider and wider. 

Stanley panted on top of him, pressing Ford down harder. He clenched and Stanley was definitely swelling and Ford had to force himself to relax, his rim stretching and he felt so _full_. 

“Stanley…” Ford gasped out, jerking himself, on the edge of climax and he was pushing back into his brother, meeting his shallow thrusts and fucking himself as hard as he could. “Stanley, Stanley, Stanley,” he whispered his brother’s name over and over again, eyes shut so tight as his body curled in on itself. “ _Oh, Stanley_!” 

Something popped into Ford and he gasped, his hole twitching as the knot slipped in. It seemed Stan would be the first to blow and Ford groaned, feeling warmth gushing inside of him, much more than a human would be able to produce and Ford jerked himself hard and fast, so close, so close, so close. Stan dug his claws into Ford’s shoulder and Ford felt the tightness in his gut bursting. He writhed beneath Stan and cried out, jerking and pushing his hips back, fucking himself through his orgasm on Stan's rapidly expanding knot. 

They collapsed, Stan heavy and hot on top of him. Ford was grinning, even as his body started to ache from the exertion. A big, wet tongue lapped over his shoulder, and it throbbed, but Ford could tell that the scratches weren’t deep. This had been lovely, and exactly the sort of thing Ford apparently needed, feeling his mind clear of the exhaustion that had been plaguing him the last few days. 

Stanley’s strong front legs came over Ford’s shoulders, his claws digging into the mossy wood, pinning him in place. The cock in him was still hard and Ford groaned. It appeared that Stanley wasn’t satisfied with just one round and Ford smiled; that was just fine with him, even if he were thoroughly spent. His brother started moving again and Ford groaned, the cock knot pulling at his entrance, and he was mildly worried about him popping out, but he was so relaxed and so hot… 

They had a shallow fuck and Ford could only groan, feeling his brother's knot sliding over his prostate and oh... Oh he was orgasming again, his cock soft and… 

Ford cried out loud, spasming as he felt Stan spilling. He felt so full, stomach slightly distended as more cum pumped into him and they collapsed for good this time. They were breathing hard, Ford grinning as his consciousness faded off. 

Ford was only vaguely aware as he felt Stan slip out of him, still in wolf form. It probably wasn't the wisest decision to sleep out here in the forest but, neither of them had the strength to move and Ford felt safe enough with Stanley curled up around him, Ford laying on his hip. 

The sun came up, the moon fading away and Stanley finally turned back into his human form, Ford blinking his sleepy eyes open. It looked painful, the way his brother would pant, on his hands and knees as everything shifted. Bones popping, fur disappearing, his tail shrinking back into his tailbone and spine. Pity, Ford rather liked the tail. And the ears were cute, too. 

Stanley crawled over to him, naked and glistening with sweat. He plopped himself on top of Ford and Ford tried not to grimace and push Stanley away, no matter how gross and uncomfortable he was. 

"So... How'd ya know which one was me?" Stanley asked around a yawn and Ford ran his fingers through short grey hair absentmindedly. Stanley's body was thick and heavy, still covered in, what Ford considered, an abnormal amount of body hair. 

"That other werewolf didn't have enough chest hair." Ford smiled to himself. 

"Oh come on, Sixer!" Stanley was laughing, sounding tired, but he looked happy. 

"And that other werewolf _definitely_ didn't have enough back hair." 

"Oh shut up, ya big smart-assy jerk," Stanley laughed against him and Ford grinned more. Ford knew he had to make more of an effort to understand Stanley, if they were going to work through the lycanthropy. 

After all, Stanley was strange enough before being bitten by a werewolf and now… 

Stanley was snoring and Ford just smiled, massaging his fingers through his brother's short hair. 

Well. Stanley was just... Stanley. And that was always an adventure, one that Ford wanted to keep having.


End file.
